Patent GB-889825-A (GB)
Title: Improvements in or relating to x-ray apparatus
IPC: G03B42/02
Filed: 1958-04-21
Abstract: 889,825. X-ray apparatus. SIEMENS-REINIGER-WERKE A.G. April 21, 1958 [April 20, 1957], No. 12644/58. Class 98(1). X-ray spot film apparatus comprises a cassette carriage arranged for movement into a viewing field of the apparatus and including a device having two parts for calipering a cassette placed in the carriage and relatively displaceable in the direction, of the cassette carriage movement so as to determine the size of the selected cassette, means disposed outside the carriage for limiting the movement of the carriage, an adjusting device also outside the carriage and associated with the limiting means, and transmitting means between the cassette calipering device and the adjusting device whereby the latter is set in accordance with the size of the selected cassette. As shown, the spot film apparatus comprises a housing 8 for a fixed fluorescent screen 12 (Fig. 1 not shown), a movable diaphragm 70 and a cassette carriage which may be brought at will into the exposure field in front of the screen, the housing being supported by eyes from an arm on a carriage displaceable along a support for a patient under examination. The cassette carriage consists of a frame 13 and a cassette holder 10 having a handle 14 both mounted for movement along parallel guide rails 21 (Fig. 1 not shown) and 22 and movable relatively to one another to clamp between them a cassette 32 supported by arms 25, 26 slidably mounted under spring control on guides 27, 35 forming the holder 10 which is shown complete in Fig. 3, the arms 25, 26 bearing racks 28, 29 engaging a pinion 30 on a plate 10 relatively to which the arms 25, 26 move equal opposite distances, and which may be held in a chosen vertical position in the holder 10 by a catch pin 87 engaging in a chosen one of the detent holes 88 in the guide 35. Depending from the lower member 38 of the holder 10 is a pin 45 which rides in a spiral groove 44 in a roller 43 slidably mounted on a square shaft 46. Horizontal movement of the holder 10 relative to the frame 13 for inserting a cassette between the arms 25, 26 thus rotates the shaft 46 and so through gears 49, 50, coupling 61, 62 and pin- and-slot connection 57 rotates a shaft 56 carrying a tube 53 bearing abutments for engagement by a block 66 on the bottom of the frame 13. When the cassette is clamped between the holder 10 and the frame 13, these two members may be latched together by a pin 65 (Fig. 5 not shown) engaging in one of the recesses in the member 64 on the frame 13 so that they can be moved as a single carriage by the handle 14. Fig. 6 shows a tube 53 developed to a flat surface adapted for four different cassette sizes. For. a single exposure on the cassette area the diaphragm 70 is moved out of the exposure field so opening a switch 67 and rendering stepping relays 74, 75 for the shaft 56 inoperative whereupon one of the stops 54<SP>1</SP> is disposed in the path of the block 66 to centre the cassette in the exposure field when the cassette carriage is moved into it from the ready position shown. For serial radiography the diaphragm 70 is, moved into the position shown, closing the switch 67. Thereupon movement of the frame 13 into the exposure field causes switch 68 to close energizing relays 74, 75 so that the tube 53 is rotated to bring one of the stops 54R into the path of the block 66 to arrest the cassette carnage with the left hand half of the cassette centrally aligned in the exposure field, the tube 53 being carried to the left a short distance as allowed by compression of its positioning spring 78 so that the boss 79 on the shaft 56 opens the switch 69 de-energizing the stepping relay 74 while the shaft is held against back rotation by the relays 75. After the exposure the cassette carriage is returned towards the right but, switch 69 having reclosed so that relay 75 has rotated tube 53, its return to the ready position is prevented by a stop 55 on the tube 53. On again moving the cassette carriage to the left, it is arrested by a stop 54L for exposure of the other half of the cassette, whereafter the cassette carriage may be returned to the rest position reopening the switch 68 and de-energizing both the relays 74, 75 so that the spring 63 joining the coupling members 61, 62 returns the tube 53 to its initial position. Different radiographs may be made on the upper and lower halves of the cassette by employing a further diaphragm limiting the exposure field vertically to a central part and by moving the plate 10 and the cassette-engaging arms 25, 26 vertically along the guides 27, 35 to a position in which a rotatable latch 84 may be turned downwards disengaging the catch pin 87 to engage a pin 85 on a clockwise-urged lever 94. Serial radiographs may be made on the upper half of the cassette as previously described and as the cassette carriage returns to the rest position a fixed pin 98 engages a lever arm 97 which moves lever 94 anticlockwise and frees the latch 84 which however still remains in a downward position. The assembly 10<SP>1</SP>, 25, 26 is then moved upwardly under control of a dashpot 100 by the springs 31, 80 until the end 91 of a lever 90 normally held in the inoperative position shown by the latch 84 engages a depending finger on the upper member 39 of the cassette holder, thus disposing the cassette for exposure of its lower half. In another embodiment (Fig. 7, not shown), the grooved roller 43 is replaced by an electrical analogue system, the cassette holder being connected to an endless belt driving through a worm gear an emitter and a receiver operating the tube 53. In a further embodiment (Figs. 8 and 9), the corresponding control exercised by the size of the cassette is achieved by switch actuating members 109.. 114, members 109..111 closing switch 107 for one direction of movement relatively to the frame 13 and members 112..114 closing switch 108 for the opposite direction of movement. Switches 107, 108 operate relays 116 and 117 (Fig. 10, not shown) which act to drive the tube 53 in opposite directions, a ball catch device 121 preventing accidental movement..